Mars' rival will outshine Red Planet this month

One of the ways that astronomy is enriched and romanticized is through the stories behind how various stars in the night sky have received their names. Most of these tales are shrouded in mysteries that date back to the cultures of earliest antiquity. This month, however, Northern Colorado observers will have a chance to view "up close and personal" how one of the bright stars in the early autumn heavens came to receive its name.

The star of note is a reddish star that occupies the "heart" of the well-known constellation of Scorpius the Scorpion. Rather that being named as the "Scorpion's Heart" or some other similar designation, this star was named Antares, which means "The Rival of Mars." Mars, of course, is the planet with its own set of myths and legends, albeit from more recent times, and every two years or so the Red Planet passes to the north of Antares in its journey through the constellations of the zodiac. Antares, meanwhile, is a red supergiant star that would engulf all of the planets out to Jupiter were it to be placed at the center of our solar system.

The remarkable fact about these two disparate objects is that to the naked eye, they seem to have the same deep reddish-orange color, a fact that has been confirmed from more precise photometric color measurements made by astronomers. In the eyes of ancient sky-watchers the nearly identical colors of these two objects undoubtedly fueled the idea that Antares was the naturally logical choice for a celestial rival to Mars.

Usually, whenever there is a Mars-Antares conjunction, Mars glows as the brighter of the two objects. For there to be a true rivalry, however, Antares ought to win at least a few of its brightness duels with Mars as it passes by, and this October will mark one of those wins for Antares. As Mars passes by Antares in upcoming days, it will be Antares that slightly outshines the Red Planet by about 25 percent. The entire encounter can be viewed throughout October to the southwest for about two hours after sunset as Mars slowly creeps night to night across northern Scorpius. On the night of Oct. 20, Mars will be at its closest approach to Antares, and the striking similarity in the colors of the two objects is readily obvious to either naked eye or binocular observations. Take advantage of the crisp and gloriously clear autumn nights and enjoy the latest chapter in this ancient and storied celestial rivalry.

Elsewhere in the sky: The planet Jupiter rises about 10 p.m. and can be seen to the northeast, standing out as a yellowish-white object amidst the stars of Taurus and just to the northeast of the much fainter ruddy first magnitude Taurus star Aldebaran.

The planet Venus currently rises about 3 a.m. to the east and gleams this month in the constellation of Leo the Lion, easily outshining that constellation's brightest star Regulus which it passed by a few days ago.

The first quarter moon will have already set for the peak nights of the Orionid meteor shower which will occur between Oct. 20 and Oct. 24. On these nights, an observer should be able dawn to see approximately 20 meteors per hour between midnight and dawn from a dark sky site

The planets Mercury and Saturn are too close to the sun to be easily seen in October.

Roger Culver is an astronomer who teaches at CSU. He has also been a member of the IAU for nearly 30 years. Write to him at the Department of Physics, Colorado State University, Fort Collins, CO 80523-1875.

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Colorado Skies

Colorado State University astronomy professor Roger Culver clues you in on what's happening in the night sky. His column runs the first Sunday of the month.

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Mars' rival will outshine Red Planet this month

One of the ways that astronomy is enriched and romanticized is through the stories behind how various stars in the night sky have received their names. Most of these tales are shrouded in mysteries